Yup Ace, I initially installed most of the TransGo TFOD-518 kit some years ago. I say most as when it was installed, I did it with the transmission in the truck and as such. the OD section was not dropped so as to allow removal of the rear servo's fulcrum pin, . . . so as to allow installation of the mods for that servo. Make sense?
I installed the rest of the kit when I overhauled the trans last year.
Anyhoot, the trans has worked perfectly since that time. However, with the installation of the twins, and the subsequent gain of an additional 100ft/lbs of torque, the trans wants to slip during the engagement of each gear under WOT conditions. It's not much, but if left un-addressed, it will burn the clutches/band.
Further, the peak of the power curve has shifted up the RPM band a bit and as the trans sits, it's shifting gears
under the power peak. I need to raise the WOT shift points a couple hundred RPMs.
So with researching things lately, I've found that TransGo has revised the kits so as to have something more appropriate for the diesels. In fact, the
earlier TFOD series of kits are now not recommended for our trucks. This includes the TFOD-HD. I'm told by the folks at TransGo, said kits are intended for the lock-up line of A518/618 transmissions. The kits will work, but there will be a lot of left over parts.
Naturally, I found this out after I bought the SK-TFOD Diesel kit recently. Again, the kit will work, but it's also based on the lock-up versions of the A518/618. More left over parts.
The folks at TransGo say that for our limited run of non lock-up A518s, the SK-TFOD-Jr is best suited.
Now here's the fly in the ointment, none of the TransGo kits are intended for the Drag-Race application. They are more suited to the working truck that is pulling a heavy load, with amended power that is high enough that in some instances, transmission shafts are being broken with the typical "Bang-Box" shifts. TransGo has designed the latest kits so as to have our trans shift more like an Allison. A kind of "Bump and slide" shift. The emphasis is placed on a quick shift with little gear over-lap.
Crap, from what I'm seeing in these kits as well as from that I've gleaned from the WWW, most use similar methods of modifying the valve-body. Blocker-rods and springs to modify the application of the servos, as well as the cushioning effects of the accumulators. Said workings are further modified by altering the metering orifices (holes) in the separator plate.
The one thing that's got me in all of this is keeping the different modes of valve-body workings sorted.
For example: (The TransGo kits deal more with part-throttle situations)
- Most offer springs/mods for the throttle Valve assembly that include the ability to alter the shift points. The instructions are vague in that they don't make it clear that they are talking about
Part-Throttle shift points. The later SK-TFOD is designed so that the driver who sports a bigger hair-drier can raise the shift points a little thus allowing the turbo to better spool in a given gear. This is NOT applicable to a WOT situation specifically.
But then again the TV works in conjunction with the mechanical governor and line pressure. All of which are dynamic.
DOH!!!
Clear as mud?
